Pantograph apparatus



Nov. 18, 1952 c. THUMIM PANTOGRAPH APPARATUS 3 Sheets-Sheet 1 Filed June '7, 1950 INVENTOR CARL THUMIM BY M/ m ATTORN EYS Nov. 18, 1952 c. THUMlM 2,618,682

PANTOGRAPH APPARATUS Filed June 7, 1950 3 Sheets-Sheet 2 x Ka n;

INVENTOR C ARL THLJMIM ATTORNEYS Patented Nov. 18, 1952 PANTOGRAPH APPARATUS Carl Thumim, Yeadon, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application June 7, 1950, Serial No. 166,643

2 Claims.

My present invention relates to circuit breakers, and more particularly to a pantograph apparatus for mounting the circuit breaker in a cubicle in such manner that the circuit breaker may be moved to its operative position or to its test position while it is at all times fully supported in full vertical position.

Heretofore, pantog-raph mounted circuit breakers have been relatively loosely mounted owing to the fact that the panel is in efiect supported at the ends of pairs of long lever arms, one pair at each side.

The primary object of my invention is to integrate the pairs of lever arms of the pantograph mounting mechanism to provide a rigid interbraced structure in which the opposite sides of the pantograph support will reinforce each other and of necessity move simultaneously.

Another object is to eliminate slidable guides which are difiicult and expensive to fit and cause undesirable friction.

The foregoing and many other objects of my invention will become apparent in the following description and drawings in which Figure 1 is a side view partly in cross-section of a cubicle tor a circuit breaker having the pantograph mechanism of my invention with the circuit breaker in racked-out position.

Figure 2 is a side View partly in cross-section of a cubicle for a circuit breaker having the pantograph mechanism of my invention with the circuit breaker in racked-in or operative position.

Figure 3 is a top plan view partly in section taken on line 3-3 of Figure 1 showing the methpantograph mechanism.

Figures 4, 5, 6 and 7 are cross-sectional views taken, respectively, on lines |-'4, -'5, B6, and 'l-| of Figure 1 looking in the direction of the arrows.

Figure 8 shows a geometrical analysis of the minimum devices required to obtain the ideal pantographic conditions.

Referring to Figure l, the circuit breaker panel l3 which is intended to carry the circuit breaker (not shown) is here shown racked-out to a test or repair position with the back connection studs I, I2 of the circuit breaker fully disengaged from the main disconnect contacts I 3, M in the cubicle.

The cubicle 5 is provided with a top wall 16, 'bot- 2 racking screw 24 is shaped to receive a rota-ting handle or other tool.

Racking screw 24 is in threaded engagement with nut 2| and rotation of screw 24 will, therefore, cause panel ID to move from the racked out position of Figure 1 to the racked-in position of Figure 2 where the back connection studs H and I2 of the circuit breaker are connected to the main disconnect contacts l3, l4. Reverse rotation of screw 24 will result in racking-out of the circuit breaker on panel H] from the position of Figure 2 to the position of Figure 1.

The panel I!) is at all times supported in vertical position by the pantograph arms 30, 3| on the left side and 32, 33 on the right side. Arms 30, 32 are the outside arms of each set and arms 3 I, 33 are the inside arms of each set. Each of the arms to 33 is a rigid member. The particular construction shown consists of a tubular member having a reinforcing insert 34 as seen in the crosssectional view of Figure 7.

The arms 30, 3| on one side and the arms 32, 33 on the other side are pivotally interconnected by bearing pin 35, 35a passing through appro- I priate registering openings in the arms 30, 3|

and 32, 33 (see also Figure 6).

A washer 36 on the pin 35 on each side spaces the arms from each other for free rotation with respect to each other. Head 31 of pin 35 holds the pin in position on one side and pin 38 in arm 32 (or 3|) as the case may be) enters an appropriateopening in the pin 35 to hold it in position on the arm 32 (or 30). Pin 38 may be carried in an opening in reinforcement 34 of the arm 30 (or 32). ed of integrating the opposite lever arms of the The front end of arm 3| and 33 on each side carries a pin 40 slidable in slots 4| in the vertical flanges 42, 43 on each side (see Figure 4) at the lower end of panel Hi.

The rear end of arm 39 and 32 on each side carries a pin 45 slidable in slots 46 in vertical flanges 41, 48 on rear wall l8 of cubicle l5.

The arms 32 and 30 are braced and connected at the front upper end by the bracin rod 50 to which they are both connected. Rod 50 is mounted in the bearing brackets 5|, 5| at the upper outer ends of panel Hi. Top bearing halves 52 are then secured over rod 50 by bolts 53 which pass through the matching bearing brackets 5|, 5|. Thus, the rod 50 may be rotatably positioned at the top rear of panel It].

The ends of arms 30 and 32 are secured to rod 50 so that the arms 30 and 32 are interbraced by rod 50 and rotate together.

Similarly, bearing halves B0, are secured at the upper front of rear wall l3. Rod I0 is mounted therein and'bearing halves 6|, 6| are secured thereover by bolts 62. The upper rear ends of arms 3|, 33 are secured to rod 13 and are thus interbraced for simultaneous operation by rod 70.

The interconnection of arms 30 and 32 by rod 50 and the interconnection of arms 3| and 33 by rod 79 ensure the simultaneous operation of the pantograph structure on each side and also imparts rigidity to the panel support.

In the foregoing I have attempted to describe a design to give adequate pantographic operation in the maintaining of the correct relation of the movable circuit breaker element to the stationary cubicle structure. I shall now present the basic essentials underlying such a device as I have detailed in the foregoing.

Reference is now made to Figure 8. Here I show the minimum pantographic devices necessary to obtain a condition wherein the circuit breaker panel 2N is parallel to rear of cubicle 2| 8 at all positions. The plane AF of the circuit breaker panel 2H3 must remain parallel to the plane BG cf the rear of the cubicle 2 l B by virtue of the pantograph members 232 and 233 acting so as to maintain the alternate interior angles formed by the lines of planes AF and BG and intersecting the lines of members 232 and 233. These angles are parts of triangles which automatically remain similar in all positions of the circuit breaker panel 2H] since the corresponding sides of the triangles formed are always equal.

The plane CE of the circuit breaker panel 2!!) must remain parallel to the plane DB of the rear of the cubicle 2l8 since the interior angles, exterior angles, and corresponding angles formed by the planes DB, BE, CE and CD are maintained at 90 by the bearing surfaces of the tie rod (4) and members 232 and 233.

Thus I have shown the minimum essentials to obtain the basic pantographic conditions desired. In the design presented by Figures 1 to '7, I have merely added members to add rigidity to the design.

In the foregoing I have described my invention solely in connection with specific illustrative embodiments thereof. Since many variations and modifications of my invention will now be obvious to those skilled in the art, I prefer to be bound not by the specific disclosures herein contained but only by the appended claims.

I claim:

1. In combination, a cubicle for a circuit breaker, a panel mounting for said circuit breaker, a pantograph mounted in said cubicle, said panel being carried by said pantograph, said pantograph comprising a first pair of rigid pantograph arms on one side of said circuit breaker, a second pair of pantograph arms on the opposite side of said circuit breaker, each of said pantograph arms being tubular and having a reinforcing insert in each tube, a first pin extending horizontally and pivotally mounting one of said first pair of pantograph arms on one side of said circuit breaker to one of said second pair of pantograph arms on the other side of said circuit breaker, a second pin extending horizontally and pivotally mounting the second of said first pair of pantograph arms to the second of said second pair of pantograph arms, said first pin being rigidly attached and rotatable with the first of said first and second pairs of pantograph arms; said second pin being rigidly attached and rotatable with the second of said first and second pairs of pantograph arms, a pair of vertical front slots at the lower end of said panel, one each on opposite sides of said circuit breaker, a pin carried at the front of one of said first pair and second pair of pantograph arms and slidably mounted in their respective front slots, a pair of vertical back slots at the lower rear end of said cubicle, one each on opposite sides of said circuit breaker, a pin carried at the rear of one of said first pair of pantograph arms and second pair of pantograph arms and slid ably mounted in their respective slots, a screw member mounted on said panel and cubicle and extending to the rear of said cubicle, a mounting for said screw member, said screw member being rotatable in said mounting but having no longitudinal movement, said panel and its circuit breaker being movable along said screw member as it is rotated and said circuit breaker being held rigidly in a vertical plane by said pantograph arms as it is moved.

2. In combination, a cubicle fora circuit breaker, a panel mounting for said circuit breaker, a pantograph mounted in said cubicle said panel being carried by said pantograph, said pantograph comprising a first pair of rigid pantograph arms on one side of said circuit breaker, a second pair of pantograph arms on the opposite side of said circuit breaker, a first pin extending horizontally from the front of one of said first pair of pantograph arms'on one side of said circuit breaker to the front of one of said second pair of pantograph arms on the other side of said circuit breaker, said front of said one of said first and second pair of pantograph arms being rigidly attached to and rotatable with said first pin, a second pin extending horizontally from the rear of the other of said first pair of pantograph arms to the rear of the other of said second pair of pantograph arms, said rear of said last mentioned arms being rigidly attached to and rotatable with a first and second pair of bearings, said first pair of bearings rotatably supporting said first pin, said second pair of bearings rotatably supporting said second pin, a pair of vertical front slots at the lower end of said panel, one each on opposite sides of said circuit breaker, a pin carried at the front of one of said first pair and second pair of pantograph arms and slidably mounted in their respective front slots, a pair of vertical back slots at the lower rear end of said cubicle, one each on opposite sides of said circuit breaker, a pin carried at the rear of one of said first pair of pantograph arms and second pair of pantograph arms and slidably mounted in their respective slots, a screw member mounted on said panel and cubicle and extending to the rear of said cubicle, a mounting for said screw member, said screw member being rotatable in said mounting but having no longitudinal movement, said panel and its circuit breaker being movable along said screw member as it is rotated and said circuit breaker being held rigidly in a vertical plane by said pantograph arms as it is moved.

CARL THUMIM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 156,383 Snow Oct. 27, 1874 1,841,278 Dallas Jan. 12, 1932 2,324,543 Scott July 20, 1943 2,420,842 Schymik May 20, 1947 

